1 files changed, 132 insertions, 0 deletions
diff --git a/hs/list.squig b/hs/list.squig
new file mode 100644
index 0000000..c5f468c
--- /dev/null
+++ b/hs/list.squig
@@ -0,0 +1,132 @@
+list_new := ??{
+	x := {
+		front := nil;
+		back := nil;
+	};
+};
+
+list_push_front := ??(list, item){
+	list {
+		if front == nil {
+			front = {
+				value := item;
+				next := nil;
+				prev := nil;
+			};
+			back = front;
+		} else {
+			front = {
+				value := item;
+				next := front;
+				prev := nil;
+			};
+		}
+	}
+};
+
+list_push_back := ??(list, item){
+	list {
+		if back == nil {
+			front = {
+				value := item;
+				next := nil;
+				prev := nil;
+			};
+			back = front;
+		} else {
+			back = {
+				value := item;
+				next := nil;
+				prev := back;
+			};
+		}
+	}
+};
+
+list_pop_front := ??(list){
+	x := nil;
+	list {
+		if front == nil {
+			throw_error("Call to 'list_pop_front' on empty list");
+		}
+		front {
+			x = value;
+			front = next;
+		}
+		if front == nil {
+			back = nil;
+		}
+	}
+};
+
+list_pop_back := ??(list){
+	x := nil;
+	list {
+		if back == nil {
+			throw_error("Call to 'list_pop_back' on empty list");
+		}
+		back {
+			x = value;
+			back = prev;
+		}
+		if back == nil {
+			front = nil;
+		}
+	}
+};
+
+list_get := nil;
+{
+	get_helper := ??(front, idx){
+		if front == nil {
+			throw_error("Index past end of list in 'list_get'");
+		}
+		y := nil;
+		if idx == 0 {
+			front {
+				y = value;
+			}
+		} else {
+			front {
+				get_helper(next, idx - 1) {y = x;}
+			}
+		}
+		x := y;
+	};
+	list_get = ??(list, idx){
+		if idx < 0 {
+			throw_error("Negative index in 'list_get'");
+		}
+		y := nil;
+		list {
+			get_helper(front, idx) {y = x;}
+		}
+		x := y;
+	};
+};
+
+list_set := nil;
+{
+	set_helper := ??(front, idx, val){
+		if front == nil {
+			throw_error("Index past end of list in 'list_set'");
+		}
+		if idx == 0 {
+			front {
+				value = val;
+			}
+		} else {
+			front {
+				set_helper(next, idx - 1, val);
+			}
+		}
+	};
+	list_set = ??(list, idx, val){
+		if idx < 0 {
+			throw_error("Negative index in 'list_set'");
+		}
+		list {
+			set_helper(front, idx, val);
+		}
+	};
+};